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Computer Network Assignment A133808
INTRODUCTION The internet has had a relatively brief, but explosive history. It grew out of an experiment begun in the 1960s by the U.S. Department of Defense. The DoD wanted to create a computer network that would continue to function in the event of a disaster, such as a nuclear war. If part of the network was damaged or destroyed, the rest of the system still had to function. That network was called ARPANET, (Advanced Research Projects Agency Network) which linked U.S. scientific and academic researchers, the forerunner of today's Internet. BACKGROUND A computer network (also called as a network) is a group of computers and devices interconnected by communications channels that facilitate communications among users by means of a share communication link. In information technology, a network is a series of points or nodes interconnected by communication paths. Networks can interconnect with other networks and contain subnetworks. The most common topology or general configurations of networks include the bus, star, Token Ring and mesh topologies. Networks can also be characterized in terms of spatial distance as local area networks ,metropolitan area networks, and wide area networks (WANs). A given network can also be characterized by the type of data transmission technology in use on it (for example, a TCP/IP or Systems Network Architecture network); by whether it carries voice, data, or both kinds of signals; by who can use the network (public or private); by the usual nature of its connections (dial-up or switched, dedicated or nonswitched, or virtual connections); and by the types of physical links (for example, optical fiber, coaxial cable, and Unshielded Twisted Pair. Large telephone networks and networks using their infrastructure (such as the internet) have sharing and exchange arrangements with other companies so that larger networks are created. BENEFITS Computer networking can provide services and reduce the cost of equipment of an organization. Networking Model may be server based on peer to peer. In server based network model, server receives requests from clients and provides them services, resources were managed centralized. On the other hand in peer to peer networking resources were decentralized. Through networking of computer it can be sharing of files and data on different computers and can be accessed remotely. Networking can reduce the cost of equipments of an organization through sharing printers and other devices. One printer is enough for an organization if they properly manage and handle the printer activities. Printer will be installed on a system and share it for other systems to send print from other systems. Administrator can easily perform administration tasks of whole network without going to different locations. Installation of application and other problems of systems can be solved remotely. It can be managed security of files and data of an organization.Server based network model provides better services to secure our important files and data while in peer to peer network model data and files can be secured at individual level. Some users can be restricted to access the shared files / folders and it can be secured from un authorization access of files and folders through operating system security features. It can be provide better services and support network application. For example email can be managed within and outside the organization through mail server and database client / server application can be organized through configure a database server and provide services to clients. WHAT IS NETWORK CLASSIFICATION Connection method Computer networks can be classified according to the hardware and software technology that is used to interconnect the individual devices in the network, such as optical fiber, Ethernet, wireless LAN,HomePNA, power line communication or G.hn. Wired technologies *''Twisted pair wire'' is the most widely used medium for telecommunication. Twisted-pair wires are ordinary telephone wires which consist of two insulated copper wires twisted into pairs and are used for both voice and data transmission. The use of two wires twisted together helps to reduce crosstalk and electromagnetic induction. The transmission speed ranges from 2 million bits per second to 100 million bits per second. *''Coaxial cable'' is widely used for cable television systems, office buildings, and other worksites for local area networks. The cables consist of copper or aluminum wire wrapped with insulating layer typically of a flexible material with a high dielectric constant, all of which are surrounded by a conductive layer. The layers of insulation help minimize interference and distortion. Transmission speed range from 200 million to more than 500 million bits per second. *''Optical fiber cable'' consists of one or more filaments of glass fiber wrapped in protective layers. It transmits light which can travel over extended distances. Fiber-optic cables are not affected by electromagnetic radiation. Transmission speed may reach trillions of bits per second. The transmission speed of fiber optics is hundreds of times faster than for coaxial cables and thousands of times faster than a twisted-pair wire. Wireless technologies *''Terrestrial microwave'' – Terrestrial microwaves use Earth-based transmitter and receiver. The equipment look similar to satellite dishes. Terrestrial microwaves use low-gigahertz range, which limits all communications to line-of-sight. Path between relay stations spaced approx, 30 miles apart. Microwave antennas are usually placed on top of buildings, towers, hills, and mountain peaks. *''Communications satellites'' – The satellites use microwave radio as their telecommunications medium which are not deflected by the Earth's atmosphere. The satellites are stationed in space, typically 22,000 miles (for geosynchronous satellites) above the equator. These Earth-orbiting systems are capable of receiving and relaying voice, data, and TV signals. *''Cellular and PCS systems'' – Use several radio communications technologies. The systems are divided to different geographic areas. Each area has a low-power transmitter or radio relay antenna device to relay calls from one area to the next area. *''Wireless LANs'' – Wireless local area network use a high-frequency radio technology similar to digital cellular and a low-frequency radio technology. Wireless LANs use spread spectrum technology to enable communication between multiple devices in a limited area. An example of open-standards wireless radio-wave technology is IEEE. *Infrared communication , which can transmit signals between devices within small distances not more than 10 meters peer to peer or ( face to face ) without any body in the line of transmitting. Scale Networks are often classified as local area network (LAN), wide area network (WAN), metropolitan area network (MAN), personal area network (PAN), virtual private network (VPN), campus area network (CAN), storage area network (SAN), and others, depending on their scale, scope and purpose, e.g., controller area network (CAN) usage, trust level, and access right often differ between these types of networks. LANs tend to be designed for internal use by an organization's internal systems and employees in individual physical locations, such as a building, while WANs may connect physically separate parts of an organization and may include connections to third parties. Functional relationship (network architecture) Computer networks may be classified according to the functional relationships which exist among the elements of the network, e.g., active networking, client–server and peer-to-peer (workgroup) architecture. Network topology Computer networks may be classified according to the network topology upon which the network is based, such as bus network, star network, ring network, mesh network. Network topology is the coordination by which devices in the network are arranged in their logical relations to one another, independent of physical arrangement. Even if networked computers are physically placed in a linear arrangement and are connected to a hub, the network has a star topology, rather than a bus topology. In this regard the visual and operational characteristics of a network are distinct. Networks may be classified based on the method of data used to convey the data, these include digital and analog networks. TWO TYPES OF NETWORKS BASED ON PHYSICAL SCOPE LOCAL AREA NETWORK A local network (LAN) is a network that connects computers and devices in a limited geographical area suchas home, school, computer laboratory, office building, or closely positioned group of buildings. Each computer or device on the network is a node. Current wired LANs are most likely to be based on Ethernet technology, although new standards like ITU-T G.hn alsoprovide a way to create a wired LAN using existing home wires (coaxial cables, phone lines and power lines). All interconnected devices must understand the network layer (layer 3), because they are handling multiple subnets (the different colors). Those inside the library, which have only 10/100 Mbit/s Ethernet connections to the user device and a Gigabit Ethernet connection to the central router, could be called "layer 3 switches" because they only have Ethernet interfaces and must understand IP. It would be more correct to call them access routers, where the router at the top is a distribution router that connects to the Internet and academic networks' customer access routers. The defining characteristics of LANs, in contrast to WANs (Wide Area Networks), include their higher data transfer rates, smaller geographic range, and no need for leased telecommunication lines. Current Ethernet or other IEEE 802.3 LAN technologies operate at speeds up to 10 Gbit/s. This is the data transfer rate. IEEE has projects investigating the standardization of 40 and 100 Gbit/s CAMPUS NETWORK A campus network is a computer network made up of an interconnection of local area networks (LAN’s) within a limited geographical area. The networking equipments (switches, routers) and transmission media (optical fiber, copper plant, Cat5 cabling etc.) are almost entirely owned (by the campus tenant / owner: an enterprise, university, governmentetc.). In the case of a university campus-based campus network, the network is likely to link a variety of campus buildings including; academic departments, the university library and student residence halls. BASIC HARDWARE COMPONENTS Basic Computer Components *Computer Case *RAM *Hard Drive (HDD) *Sound Card *Video Card *Power Supply (PSU) *Motherboard *Processor (CPU) *Disk Drives (CD, DVD) *Monitor *Keyboard *Mouse RAM Computer RAM is the best known form of memory your computer uses to temporarily store and access data. From the time you turn on your computer, your CPU is constantly using memory (RAM). Every time something is opened or loaded, it gets placed into RAM. This means it is put into a temporary storage area so the CPU can more easily access the information. From there it becomes a continuous cycle where the CPU requests data from RAM, processes it and then writes new data back to RAM. In most computers,this transfer of data between CPU and RAM happens millions of times every second. When an application is closed, the application itself, along with all its accompanying files is deleted from RAM. This is to make sure there is room for new data, so unless the changed files are saved to a permanent storage device, they will be lost. Hard Drive (HDD) A Computer Hard Drive is a form of Computer memory used to permanently store files and programs. Computer Hard Drives can also be referred to as; Hard Disk Drive. When using Microsoft windows a hard disk drive is often referred to as the c-drive. Most PC Hard Drives are stored in a internal drive bay at the front of the computer. Hard drives are connected inside the computer using a ATA, SATA or SCSI cable and a power cord. There are four main components to a Hard Drive: #Platters: Aluminum, glass, or ceramic dishes coated with magnetic media. These dishes are used to store data and begin to rotate when the computer is turned on. # #Head Arm: (Also known as a “Actuator Arm”) The Head Arm is similar to the arm on a record player. It allows the Hard Disk Drive to move the read / write heads to the location where the information needs to be read or written to. #Chassis: (Also known as the “Case”) A housing that helps protect and organize all components that make up the Hard Disk Drive. #Head Actuator: An electronic device controlled by a motor that moves the Head Arm to locations where it is needed. Sound Card A Computer Sound Card is an internal component in your computer that processes audio files to provide high-quality playback through the computer speakers. It can process and play most computer file formats, including MIDI, .wav, and .mp3. This means it can play both voice and music. Some PC Sound Cards are built into the computer’s motherboard (Integrated sound), but most people looking for surround sound or 3-D sound usually buy a separate sound card. This means that the initial sound card can be disabled to install a higher quality card. Most game designers use 3-D sound to provide dynamic sound that changes based on a players position in the game. 3-D sound provides sound from several directions and makes the gamer feel like they are in a more realistic environment. Surround sound is similar to 3-D sound and also has sound coming from several directions, but the sound does not change based on the listeners actions. Both the quality of a computer's speakers and the sound card affect the overall sound quality. Video Card There are two types of systems used to create video on your computer; one type is integrated video and the other is a video card. A video card is the part of your computer that is responsible for converting binary code from the CPU into a picture so you can view it on your monitor. Video Cards can also be called Computer Graphics Cards.Computer Video cards plug directly into an expansion slot on the motherboard of a computer using various slots like PCI, AGP, and PCI Express. Integrated video is a chip built into the motherboard used to run the video. Most older systems have integrated video because it is a less expensive alternative to a video card. This usually this gives poor picture quality and slows down the computer because it relies on the systems CPU and memory to run it. Newer video cards come with their own memory, cooling, and a graphics processing unit (GPU). Power Supply (PSU) A Computer Power Supply (PSU) is vital to the operation of a computer. The Power Supply converts AC current to DC current and then sends power to all of the internal components in the computer system so they can function. A Computer Power Supply is a metal box usually located inside the top backside of the computer case. The power supply is visible from the back of the computer. It is easily identified by the presence of a port for the power cable. There are three typical voltages used in a power supply: 3.3 volts, 5 volts, and 12 volts. The 3.3 and 5 volt supplies are usually used by digital circuits, while the 12 volt supplies are more typically used to supply power to fans, motors, and disk drives. Motherboard A Computer Motherboard would be like the “central nervous system”. A Motherboard can also be called a Computer Mainboard. It is the most important circuit board in the computer system. The computer motherboard contains the bus (communication circuit for the computer components), the CPU, all memory sockets, expansion slots, etc. The bus speed is a key factor in determining the overall speed of a computer’s motherboard. Keeping all of this in mind, having a high-quality PC Motherboard is essential to having a high-quality computer. Processor (CPU) A Computer CPU is, in simple terms, the “brain” of your computer. It is also known as the processor. CPU’s are used to process everything from basic to complex functions. Every time something needs to be computed it gets sent to the CPU. It attaches directly to the motherboard using a socket and is usually cooled by a heat sink or fan. Depending on the manufacturer of the computer processor, the socket types will be different. CONCLUSION Computer communication, it seems, will become a much more useful networking tool when large numbers of people with similar interests acquire access to the technology. Though it can expedite the formation of new interpersonal networks by overcoming the space and time barriers faced by traditional networking techniques, it still requires a great deal of concentrated effort and resources to get the people to use it. This problem should become increasingly minimized over the coming years as the technological innovations become more diffused throughout society. REFERENCES http://www.computerknowledgeforyou.com/ http://en.wikipedia.org/wiki/Computer_network http://www.blurtit.com/q605597.html http://www.learnthenet.com/learn-about/birth-of-the-net/index.php http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci212644,00.html